1. Technical Field
The present invention relates to an electro-optical device and an electronic apparatus.
2. Related Art
An electro-optical device that uses electronic polarization due to Kerr effect is known. The Kerr effect is a phenomenon that, when an electric field is applied, exhibits optical anisotropy which has an axis in the direction of the electric field and of which the degree is proportional to the square of the magnitude of the electric field. A known electrooptic material that exhibits the above Kerr effect is a liquid crystal material called a blue phase, for example. It has been known that a liquid crystal device (see JP-A-2000-275605) that employs a blue phase as a liquid crystal layer has a quick response speed. The blue phase exhibits optical isotropy when no electric field is applied, and exhibits optical anisotropy that is proportional to the square of the magnitude of an electric field applied under a predetermined temperature range.
Here, the liquid crystal material that exhibits a blue phase selectively reflects (selective reflection) circularly polarized light that advances toward the liquid crystal layer and that has the same rotation direction as the turning direction of the helix of the liquid crystal material. The wavelengths of selectively reflected light depend on the helical pitch and average refractive index of the liquid crystal material. Thus, when the wavelengths of selectively reflected light fall within visible light range, light that passes through the liquid crystal layer is colored by the liquid crystal layer.
Incidentally, the liquid crystal layer contains an additive chiral agent in order to improve development of a blue phase and scattering characteristics of a pseudo-isotropic phase. When the amount of additive chiral agent exceeds a predetermined amount and the helical pitch becomes short (shorter than or equal to 500 nm), a blue phase appears. In addition, as the amount of additive chiral agent is increased, the wavelengths of selectively reflected light become short.
In the above existing liquid crystal device, however, the following problems remain unsolved. That is, as the amount of the additive chiral agent is increased to set the selectively reflected wavelengths to a shorter wavelength side with respect to the visible light range, the chiral agent is deposited. In addition, since the saturation voltage of a cholesteric blue phase is shifted to a high voltage side, an electric field of a higher magnitude is required to drive the cholesteric blue phase. Furthermore, even when the selectively reflected wavelengths are set to a shorter wavelength side with respect to the visible light range, the selectively reflected wavelengths are shifted into the visible light range because of a change in temperature and, as a result, may decrease the contrast.